Recent FDA regulations will require that aspirin tablets and a number of items be packaged in special containers which have "childproof" features. The containers must not be openable by children under a certain age in a certain number of attempts to open the containers. Satisfactory closures have been developed for bottle-type containers for aspirin and prescription drugs and other items which may be potentially dangerous to children. However, difficulty has been encountered in producing a satisfactory rectangular, two-piece, hinged, conventional container for packaging tablets. The problem has primarily been one of developing a container which has a consistent opening pressure, such that only pressure applied by an adult can open the container.
The utilization of conventional metallic containers is unsatisfactory as the latches provided, usually a projection on the lower section and an indentation on the upper section into which the lower indentation fits, are not selective enough so that the container cannot be opened by a child. Adapting the metal container for "childproof" latches is economically impractical as the metal from which the containers are made is not suitable for such complex latches.
Plastic containers offer an attractive alternative in providing a "childproof" container. Complex latches are possible without overly burdensome cost and plastic materials are generally in good supply. Suitable plastics are those such as polypropylene, polyethylene, vinyl chloride, etc. Generally these plastic containers will have a bottom section, a top section overlying the bottom section and hinged to the bottom section. The two sections are latched together by a latching assembly which generally includes, a protuberance projecting from the outside front wall surface of the bottom section and a recess in the inside wall of the front portion of the top section. The recess is designed to accommodate the protuberance. Pressure on the back of the container releases the latch for opening.
As advantageous as these types plastic containers have proven to be, they still suffer from one annoying problem which relates to the tendency of most plastics to "coldset". "Coldsetting" is defined as the characteristic of plastic which causes the plastic to be biased to a position in which the plastic has been held for a period of time. In the case of containers, since the containers are usually stored in the closed position, "coldset" biases the container to remain closed even after the latching mechanism has been actuated to open the container. Thus when the user presses down on the container at its rearward corners, the latches unlatch but due to the "coldset" of the hinge holding the upper section to the lower section, the latches will tend to relatch.
Therefore it is an object of this invention to provide a plastic "childproof" container having latches holding the container closed which are capable of remaining in the open mode irrespective of whether or not the resilient hinge has a "coldset" biasing the container to the closed position.